Unit Implementation Strategies
The first part of my unit involves introducing the concept of size and measurement. On the first day, I plan to discuss and demonstrate to my students the units of the metric system and then have them develop the skill of measuring accurately. I am going to teach them that the metric system is based on the power of ten and provide concrete examples of items that they can relate to that are for example a meter, a centimeter, and a millimeter. I will then allow them (individually and in groups) to practice their measuring skills in order to gain a comfortable background knowledge. They are going to be presented with several objects: they must first make a prediction of the length and then actually measure the object in SI units. Afterwards, we will discuss as a class the items that they measured and the relationship of their measurement to their prediction. This part of the unit focuses on macroscopic measurements, but the next part of this lesson involves discussion of things they cannot see with the unaided eye, such as those things that must be measured in micrometers and nanometers. The next step is to have the students relate those things they cannot see unaided to their relative size or length. Two good sites for this demonstration are referred to in the appendix. Next we will observe the sites and discuss the relationship of meters to nanometers. To conclude this part of the unit, I am going to have my Honors Biology students read an excerpt from J.B.S. Haldane's essay On Being the Right Size. After reading the essay, my students will be asked to write a paragraph discussing how size and scaling would impact the ability of a human to function if he or she was either six centimeters tall or six meters tall (they can choose between on of the two). After they have written and shared their individual responses with the class as a whole, the students will get together as a group and discuss the impact of being six centimeters or six meters on the daily survival of human beings. For example, how would an extremely large or extremely small human eat or drink? Where would he or she sleep? Would he or she be able to function in the world we live in today as we do? They will then list and share what they have discussed with the rest of the class. This section of the unit will probably cover a two block class period.
The second part of my unit will involve using an article by Michael C. LaBarber entitled The Biology of B-Movie Monsters. This is a wonderful article which presents B-movie creatures and explains their structure and the physics of their function, which is often different than depicted in the movie. Examples range from the small, The Incredible Shrinking Man (1957), to larger creatures, King Kong (1933). LaBarber divides his paper into sessions; in the first session, he discusses the relationship between biology and geometry in scaling. He uses this relationship to explore how physiological relationships are affected by a change in size. In session two, LaBarber discusses the effects of scaling down or being smaller on an organism. He gives the example of the shrinking man-"the surface area of his body, through which he loses heat, has decreased by a factor of 70 x70 or about 5,000 times, but the mass of his body, which generates the heat, has decreased by 70 x70 x 70 or 350,000 times. He is clearly going to have a hard time maintaining his body temperature unless his metabolic rate increases drastically."
Session three of LaBarbera's article deals with the other end of the spectrum, creatures that are enlarged in size. He actually refers to Haldane's essay and discusses the strength of bone. "The strength of a bone is approximately proportional to its cross-sectional area; this is simply another way of saying that there is a maximum mechanical stress, or force per unit area, that a bone can withstand." The load the bone must bear is proportional to the mass of the animal& hellip;the load on the bone will increase in proportion to the increase in volume(length cubed), but the cross-sectional area of the bone will only increase as length squared& hellip;the animal's bones would break under its own weight." He goes on to discuss how posture and bone density affects an animals ability to function. LaBarbera has several more sessions, but I am going to focus on the first three, time permitting.
The strategy for this section of my unit is to have the students read each of the three sessions in the article, watch 3-5 minute clips from You-tube of each of the movies, and discuss the concepts presented. The students will then be presented with an assignment in which they will design their own movie monster and justify the feasibility of its survival at its particular size. This activity will be individual projects for my Honors students and a group project for my English as Second Language learners. The students will design their creature and present their project on a poster before the class using, as their guide, a rubric presented to them beforehand. While they are presenting, their classmates will also have the same rubric to critique the presentation. This keeps the entire class engaged through all of the presentations. Upon the completion of this activity, I feel that my students will have a reasonable knowledge of size, measurement, and scaling as it relates to our study of biological system. They will be better able to make these associations as we study organisms from viruses and bacteria to elephants and blue whales. This section of the unit should be covered in 2 block classes.
The final part of my unit will incorporate the science of nanotechnology into the unit I already teach on biotechnology. I will discuss the theory behind nanoscience and present to them some practical applications of how nanotechnology is being used today. In my biotechnology unit, we discuss recombinant DNA using bacteria and plasmids. I will add that plasmids and restriction enzymes are also being used in nanoscience, in creating nanoparticles with biological activity. Our instructor in this seminar, W.Mark Saltzman, presented to us the work that he is doing with nanoparticles and cancer delivery; I want to share this work with my students. Next I want to explain and demonstrate how micelles are formed and the concept of selfassembly. As an activity for this section students in groups will dump Cheerios cereal into a container of water and observe them over a period of time: it is well-known that they will self assemble into hexagonal patterns (this can also be done with Trix cereal or sliced hotdogs). After we inquire, we will make some predictions as a class as to why this phenomenon exists. I am going to present some of the articles which can be found in the appendix from Science Daily which present various products which have been and are being developed in the field of nanotechnology today. There are several articles which present negative views on the use of nanotechnology so my students are going to have to read each and in groups discuss the pros and cons, later sharing with the entire class. This section of the unit should only take one block class period.
All three sections of this unit should take about one week total to complete. In North Carolina, Biology is an End of Course class and we are on a pacing guide; however, I feel that the time spent on this unit will pay off in the long run in that my students will be able to move through this course with increased background information and a better understanding of many of the concepts and applications that will be covered in this unit. This unit will also lay valuable groundwork as these students move through their other courses beyond biology class.
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